• 대한교통학회지
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• 제28권6호
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• pp.159-166
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• 2010

통행분포(trip distribution)에서는 첫 단계인 통행발생(trip generation)에서 구해진 통행 유출량(trip production)과 통행 유입량(trip attraction)을 연결시키는 작업이 행해진다. 즉 하나의 존에서 유출되는 통행량을 다른 존에 분포시키는 과정이라 할 수 있다. 그런데, 통행분포모형에 사용되는 통행시간이나 비용 등의 통행저항들이 통행수요가 변함에 따라 함께 변함에도 불구하고 현재 사용하고 있는 중력모형에서는 이를 고려하지 못하는 한계를 갖고 있다. 즉, 목적지까지의 통행비용이 커지면 통행수요는 줄어들며, 반대로 통행비용이 적으면 통행수요가 커지는 것과 같은 관계가 존재하게 된다. 이런 측면에서 본 연구는 통행분포시 목적지간에 균형(equilibrium condition of trip distribution)이 존재함을 증명한다. 이를 위하여 대표적인 통행분포모형인 중력모형을 이용하여 통행분포시 균형조건을 유도하며, 이런 균형조건을 만족시키는 통행분포를 구하는 방법론을 제시한다. 또한, 본 연구에서 제시된 모형은 간단한 예제를 통하여 평가하며, 통행분포시 균형상태의 해가 도출됨을 확인한다.

• Journal of Microbiology and Biotechnology
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• 제10권4호
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• pp.470-475
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• 2000

Genetic chracterstics of the structural gene of guamerin (a novel elastase inhibitor from Korean leech), integrated into the HIS4 locus of chromosomal DNA of Pichia pastoris along with the $\alpha$-factor leader sequence, were investigated. In the selected clone from candidates, two copies of the integration cassette including the structural gene copies of the integration cassette including the structural gene of guamerin were found in the integration site of the chromosomal DNA of P.pastoris. It was demonstrated that the integrated structural gene of guamerin was stable up to about 70 generations in the relay flask culture. Then, a high-cell-density culture could be fulfilled easily by DO-stat fed-batch culture, in which the cell growth and the recombinant guamerin production reached about 250 of OD600nm and 260 mg/l, respectively. Finally, it was revealed that the DNA sequence of the integrated structural gene of guamerin in P. pastoris was maintained correctly in the end of production cells of relay flask culture and high-cell-density culture.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권5호
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• pp.341-346
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• 2001

For the purpose of mass producing Monascus red pigments optimum medium composition and environmental conditions were investigated in submerged flask cultures. The optimum carbon and nitrogen sources were determined to be 30g/L of glucose and 1.5 g/L of monosodium glutamate (MSG). Of the three metals examined, Fe$\^$2+/ showed the strongest stimulatory effect on pigment production and some stimulatory effect was also found in Mn$\^$2+/. Optimum pH and agitation speed were determined to be 6.5 and 700 rpm, respectively. Under the optimum culture conditions batch fermentation showed that the maximum biomass yield and specific productivity of red pigments were 0.20 g DCW/g glucose and, 32.5 OD$\sub$500/g DCW$\^$-1/h$\^$-1/, respectively.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권1호
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• pp.54-57
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• 2003

H$_2$-producing bacteria were isolated from anaerobic granular sludge. Out of 72 colonies (36 grown under aerobic conditions and 36 under anaerobic conditions) arbitrarily chosen from the agar plate cultures of a Suspended sludge, 34 colonies (15 under aerobic conditions and 19 under anaerobic conditions) produced H2 under anaerobic conditions. Based on various biochemical tests and microscopic observations, they were classified into 13 groups and tentatively identified as follows: From aerobic isolates, Aeromonar spp. (7 strains), Pseudomonas spp. (3 strains), and Vibrio spp. (5 strains); from anaerobic isolates, Actinomyces spp. (11 Strains), Clostridium 5pp. (7 strains). and Porphyromonas sp. When glucose was used as the carbon substrate, all isolates showed a similar cell density and a H$_2$ production yield in the batch cultivations after 12 h (2.24-2.74 OD at 600 nm and 1.02-1.22 mol H$_2$/mol glucose, respectively). The major fermentation by-products were ethanol and acetate for the aerobic isolates, and ethanol, acetate and propionate for the anaerobic isolates. This study demonstrated that several H$_2$ producers in an anaerobic granular sludge exist En large proportions and their performance in terms of H$_2$ production is quite similar.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권5호
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• pp.379-381
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• 2000

Anaerobiospirillum succiniciproducens requires expensive complex nitrogen sources such as yeast extract and polypeptone for its growth and succinic acid production. It was found that A. succiniciproducens was able to grow in a minimal medium containing glucose when supplemented with corn steep liquor (CSL) as the sole complex nitrogen source. The concentration of CSL had a significant effect on the glucose consumption by A. succiniciproducent. When 10-15 g/L of CSL was supplemented, cells were grown to an OD(sub)600 of 3.5 and produced 17.8 g/L succinic acid with 20 g/L glucose. These results are similar to those obtained by supplementing yeast extract and polypeptone, thereby suggesting that succinic acid can be produced more economically using glucose and CSL.

• Journal of Microbiology and Biotechnology
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• 제3권2호
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• pp.134-138
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• 1993

Monascus anka 732Y3 was induced from Monascus anka KFCC 11832 (IFO 4478, ATCC 16360) by ultra-violet light irradiation. The growth of this new fungus is frequently more dependent on sexual propagation than asexual propagation, compared with that of its parental strain, M. anka KFCC 11832. Less conidia than those of M. anka KFCC 11832 were observed by a microscope. The optical density of the red pigments ($OD_{500}$) produced by M. anka 732Y3 was 157, which was about 10 times higer than that of M. anka KFCC 11832. Such high production of the red pigments by the mutant could be explained by the following observations.

• 한국가금학회지
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• 제40권3호
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• pp.253-262
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• 2013

본 연구는 오리사의 바닥 형태와 난방 방법에 따른 오리의 성장 특성 및 사육 환경의 변화 양상을 비교 분석하기 위하여 수행하였다. 3처리 4반복에 반복구별로 육용오리 25수씩 총 300수를 공시하여 6주간 시험을 실시하였다. 평사 직접 난방은 일반적인 사육 방식으로 설치하였고, 바닥 난방은 PVC 파이프를 이용해 온돌식 난방으로 설치하였다. 고상식 처리구는 플라스틱 망을 지상에서 50 cm 정도 높이에 고정하여 오리분이 바닥으로 통과하여 배출되도록 하였다. 6주령 생산성에서 체중 및 사료 섭취량은 처리구간에 유의적인 차이는 나타나지 않았으나, 사료 요구율은 고상식 직접 난방이 평사 직접 난방에 비하여 유의적으로 높게 나타났다(p<0.05). 도체율 및 부분육의 비율은 평사 바닥 난방에서 복강 지방량이 0.8%로 가장 낮은 것을 제외하고 전반적으로 처리구 간에 큰 차이는 나타나지 않았다. 3주령부터 5주령까지 오리사 내 이산화탄소와 암모니아의 농도는 평사 직접 난방이 다른 처리구에 비하여 높게 측정되었다. 평사에서 깔짚 수분 함량은 직접 난방이 바닥 난방에 비해 높게 나타났으나, 이와 반대로 공기 중 분진량은 바닥 난방에서 높게 나타났다. 직접난방 처리구에서 연료 소모량은 고상식이 평사에 비하여 6주 동안 약 21% 적게 소모되었다. 오리의 외관 상태를 관찰한 결과, 오리가 깔짚과 플라스틱 망의 영향을 받아 뒤로 눕거나 다리 벌림, 발목이나 다리가 휘는 현상, 발바닥 상처 등 특이 증상이 일부 관찰되었다. 3주령과 6주령에 조사한 혈구 분석 결과는 처리구간 유의적 차이는 나타나지 않았다. 본 실험 결과, 일반 농가에서 사용하는 평사 직접 난방에 비하여 바닥 난방이나 고상식 바닥의 오리사 시설은 생산성에서 유의적 효과는 나타나지 않았으나, 일부 환경 개선이나 오리의 상태 변화에 긍정적 영향을 미치는 것으로 판단된다. 그러나 현재까지 오리사 시설에 대한 연구가 매우 부족하다는 점을 감안할 때 향후 추가적인 연구를 통한 시설개선 노력이 필요할 것으로 사료된다.

• 한국미생물·생명공학회지
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• 제47권2호
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• pp.220-233
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• 2019

Bacterial lysates have become a common ingredient for natural health care. Lactic acid bacteria (LAB) could serve as potential candidates for lysate production: the lactic acids produced by LAB have been utilized for their moisturizing, antimicrobial, and rejuvenating effects, while other substances provide topical benefits and health effects for the skin. Our study aimed to obtain lysate from a LAB S. macedonicus MBF 10-2 through an optimized fermentation using the Response Surface Methodology. Strain MBF10-2 was cultivated in a 2L fermenter tank in de Man Rogosa and Sharpe (MRS) medium and in plant-based peptone modified MRS, i.e. Soy-peptone and Vegitone. The duration and the medium composition (dextrose and soy peptone or proteose peptone) were adjusted to obtain an optimum production of cell lysate. Central Composite Design was employed for Design Expert 7.0.0 by adjusting 3 factors: dextrose (1%, 1.5%, 2%, 2.5%, 3%), soy or proteose peptone (0.5%, 0.75%, 1%, 1.25% and 1.5%), and duration of fermentation (8, 10, 12 14, and 16 h for MRS-Soy peptone and 15, 17, 19, 21, and 23 h for MRS Vegitone). Bacteriocin-Like Inhibitor Substance activity of lysate and pH were used as indicators. The optimum condition for lysate production using MRS Soy Peptone and Vegitone are as follows: dextrose concentration 2.5%, plant-based peptone 1.25%, while optimum fermentation duration were 11.18 h (MRS Soy Peptone) and 17 h (MRS Vegitone) with a starter concentration of 10% at $OD_{600nm}$ $0.2{\pm}0.05$. However, the standard MRS medium produced better quality lysate compared to MRS plant-based peptones.

• Journal of Microbiology and Biotechnology
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• 제31권10호
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• pp.1430-1437
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• 2021

Cronobacter sakazakii is an opportunistic pathogenic bacterium found in powdered infant formula and is fatal to neonates. Antibiotic resistance has emerged owing to overuse of antibiotics. Therefore, demand for high-yield bacteriophages as an alternative to antibiotics has increased. Accordingly, we developed a modified mass-production method for bacteriophages by introducing a two-stage self-cycling (TSSC) process, which yielded high-concentration bacteriophage solutions by replenishing the nutritional medium at the beginning of each process, without additional challenge. pH of the culture medium was monitored in real-time during C. sakazakii growth and bacteriophage CS01 propagation, and the changes in various parameters were assessed. The pH of the culture medium dropped to 5.8 when the host bacteria reached the early log phase (OD₅₄₀ = 0.3). After challenge, it decreased to 4.65 and then recovered to 4.94; therefore, we set the optimum pH to challenge the phage at 5.8 and that to harvest the phage at 4.94. We then compared phage production during the TSSC process in jar-type bioreactors and the batch culture process in shaker flasks. In the same volume of LB medium, the concentration of the phage titer solution obtained with the TSSC process was 24 times higher than that obtained with the batch culture process. Moreover, we stably obtained high concentrations of bacteriophage solutions for three cycles with the TSSC process. Overall, this modified TSSC process could simplify large-scale production of bacteriophage CS01 and reduce the unit cost of phage titer solution. These results could contribute to curing infants infected with antibiotic-resistant C. sakazakii.

• 한국임상수의학회지
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• 제30권6호
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• pp.403-408
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• 2013

본 연구의 목적은 in vitro 실험에서 human dermal fibroblast cell을 이용한 섬유아세포 증식과 콜라겐 생성을 통한 전층피부창상치유에 대한 효과를 알아보는 것이다. In vitro 실험에서, 베타글루칸 및 양성대조물질 oncostatin M을 사용하여 처치 후 24 또는 48시간 이후 MTT assay와 세포수 관찰을 통해 섬유모세포 증식효과에 대해 평가하였다. Procollagen 생산에 대한 효과를 평가하기 위해 베타글루칸 및 양성대조물질 oncostatin M 처치 48시간 후 hydroxyproline을 HPLC를 이용하여 정량하여 평가하였다. 창상재구축에 대한 효과를 평가하기 위해 베타글루칸 및 양성대조물질 fucoidan fraction 7을 FPCL 모델을 이용하여 평가하였다. 베타글루칸 처치군은 음성대조군 대비 0.1 mg/ml 이상의 농도에서 용량의존적이고 유의적인 OD 또는 섬유아세포수의 증가가 관찰되었다. 게다가 베타글루칸 처치군은 창상면으로 유주된 세포수가 음성대조군 대비 1 mg/ml 이상의 농도에서 용량의존적이고 유의적인 증가가 관찰되었다. 그러나 베타글루칸 처치군은 음성대조군 대비 모든 용량에서 procollagen 생산에 대한 유의적인 변화가 관찰되지 않았다.